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Unread 04-07-2010, 02:46 PM   #1
I8AHUMR
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Small coolant leak around thermostat housing?

Over the last few weeks I've noticed a drop or two of coolant on my driveway every once in a while. It was getting on my lower radiator hose from somewhere and dripping from there. Nothing major and I didn't seem to lose any major amount. Anyway, I changed the coolant about a week ago before I took the jeep on vacation and since it was due. Today I noticed a green film at the joint around the input of the radiator hose on the motor. You can see it in the following picture and the area is outlined in red. It's on the underside of that joint.

Correct me if I'm wrong but that's where the thermostat is right? Haven't had to change it in the 4.0 yet. I'm guessing this is maybe the gasket? I'm running consistently at 210-215 on the highway so the cooling system seems good. Anyone run into this before? Thanks in advance...

red.jpg  
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Unread 04-07-2010, 02:51 PM   #2
5.7YJ
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Not a big problem, easy to fix. Get a new T-stat and gasket and you'll be good to go.
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Unread 04-07-2010, 03:01 PM   #3
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I just recently had to fix this but it has happened to me a few times. This last time I took the housing off I noticed the mating surface was pitted. So I took it to work where we have machines that finish mounting pads for substation connectors. It put a nice flat finish and I haven't had any issues thus far.
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Unread 04-07-2010, 03:35 PM   #4
justpicaname
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if your surface is pitted, you can always use hi heat gasket maker along with the gasket. Thats what I do, and I havn't had a leak there yet.
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Unread 04-07-2010, 06:33 PM   #5
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What ever you do, DON'T tighten it. The housing is very fragile and WILL BREAK. It is not unusual for these to start leaking over time. Take the previously given advice ^^^^^ to fix it.
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Unread 04-07-2010, 06:35 PM   #6
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When you do, make certain to put threadlocker on the bolts Been there, done that... Redid it...
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Unread 04-07-2010, 06:41 PM   #7
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The T stat housing is also a replaceable item, mine was about $19 from autohoozit. Mean Max has a type of aviation gasket sealer he swears by, I can't remember what it was but it seems to have been made by Permatex. Maybe someone will post up a link to it, or Max will see this.

Wait, here it is--google Permatex aviation form-a-gasket and it will show photos.
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yes I'm a some guy and have always put gasket sealer on my surfaces before mating
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You should go to Pirate. I hear they are real smart over there. You'd fit right in.
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Unread 04-07-2010, 06:53 PM   #8
I8AHUMR
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Yeah, I've seen the housing as a part... I believe you're referring to what Mean Max calls "yellow snot". I've seen a few posts where he swears by it.
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Unread 04-07-2010, 07:39 PM   #9
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Easy fix dude...a good 30 minute wrenching 101 project.
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Unread 04-08-2010, 01:29 PM   #10
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Quote:
Originally Posted by I8AHUMR View Post
Yeah, I've seen the housing as a part... I believe you're referring to what Mean Max calls "yellow snot". I've seen a few posts where he swears by it.
It's called weather strip adhesive made by 3M, it comes in black or yellow and it's some bad a$$ stuff!
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Unread 04-08-2010, 05:30 PM   #11
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Quote:
Originally Posted by Opihi59 View Post
The T stat housing is also a replaceable item, mine was about $19 from autohoozit. Mean Max has a type of aviation gasket sealer he swears by, I can't remember what it was but it seems to have been made by Permatex. Maybe someone will post up a link to it, or Max will see this.
Gotcha covered!

Wait, here it is--google Permatex aviation form-a-gasket and it will show photos.
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Originally Posted by 5.7YJ View Post
It's called weather strip adhesive made by 3M, it comes in black or yellow and it's some bad a$$ stuff!
Actually, I use that on valve cover gaskets. Opihi59 was correct on my choice of sealer for the T-stat gaskets.
Sometimes things just don't seal up so well, and in those cases you could stand a little help.

Here is my "secret weapon" sealer:

(MFG description)

Permatex #3 Form-a-gasket Aviation Sealer
Non-hardening liquid gasket sealant/dressing/coating is a thin, brushable dressing or sealer for close-fitting parts. Suitable for continuous temperatures to 400F (204C). Resistant to antifreeze, aviation fuels, high-detergent oils and lubricants. Conforms to MIL-S-45180 D.

Permatex Aviation Form-A-Gasket No. 3


Read the list again, yep antifreeze is on there too! You can use it on T-stat housings & radiator hoses that prove to be difficult to seal up at the radiator, heater core, or water pump fittings. This stuff is amazing, it will seal up anything and without dealing with the goopy RTV that I despise so much and NO WAITING TIME!

Just use the "brush-in-can" lid and smear a thin film on both sealing surfaces & put them together & add the fluids/oils/etc. and be on your way. Use it on oil pans, valve covers, automatic tranny pans, case halves or anywhere. It's also a great thread sealer like for drain & fill plugs too. It's Aviation and MILSPEC certified.

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Unread 04-08-2010, 05:32 PM   #12
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